The present invention relates to a copier, printer or like image forming apparatus which is implemented with the principle of electrophotography.
In a modern image forming apparatus of the type described, a plurality of replaceable image forming units, or cartridges, each including at least a photoconductive element therein are selectively loaded in a body of the apparatus as desired. Proposals pertaining to such an apparatus are disclosed in Japanese Unexamined Patent Publication (Kokai) Nos. 58-68759 and 59-77449, for example. The replaceable imge forming unit, or kit, scheme is advantageous from the cost standpoint in consideration of consumption and deterioration in function which occur in various structural elements of each of the kits. Specifically, replacing a deteriorated one of the kits with another is more economical than calling for a serviceman for maintenance and inspection.
However, for most of the users, all the possible sizes of images are not always necessary and, rather, it often suffices to provide for only some particular sizes of images depending upon the user. Concerning an apparatus capable of dealing with images of a B4 format, for example, its function could not be made most of if used to provide images of relatively small sizes such as those for cards, post cards and name cards. Such is wasteful taking into account the costs of the photoconductive element and other essential structural elements. Should the apparatus be reduced in size, on the other hand, images of relatively large sized could not be achieved.